Dugong
Order: Sirenia Family: Dugongidae Genus & Species: Duging dugong
The dugong thrives in coastal shallows where the light, sun-warmed waters promote the growth of sea grasses. It lives its life at a leisurely pace and has few natural predators.
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The dugong inhabits mostly tropical coastal waters, wherever it can find plenty of aquatic vegetation to eat. The wide distribution of the dugong suggests that the animal is capable of making marathon journeys through the open sea. Short seasonal movements are commonplace throughout the animals range. Dugongs in Western Australia's Shark Bay have been known to migrate distances of around 160km in order to avoid the low winter temperatures that affect some parts of the bay. |
Behaviour
The dugong usually rests during the day and feeds at night. It must surface every
three minutes or so to breathe air. It swims at around 10km/h but can put on short
bursts of twice this speed if disturbed.
Dugongs usually live their life either single, as a mother and calf pair, or in groups of
three to six. Congregations of hundreds can occur, usually in fertile feeding
grounds
No aggressive behaviour between individuals has been witnessed although, when alarmed,
adult dugongs are said to utter a whistling sound, while the calves are reported to bleat
like a lamb.
Occasionally, sharks may attack dugongs. When faced with a serious threat, dugongs
may bunch together to defend themselves. If the shark continues to attack, the
dugongs may counter-attack in a group by swimming at the shark and butting it to drive it
away.
| Food and Feeding The dugong is exclusively vegetarian, feeding mainly on sea grasses. It eats up to 100kg per day, processing this in an extremely long gut. It obtains energy giving carbohydrates by pulling up the roots of the grass. If grasses are in short supply, it will eat seaweed. The dugong eats by flaring its flexible lip around the base of the plants, which are then gripped and ripped out by muscular pads on the lips. |
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Breeding
Females breed only once every three to seven years, producing only one calf,
which then takes at least nine years to reach sexual maturity. A female produces no
more than about six young during her life, which hampers the recovery of populations in
decline.
A newborn dugong is about a metre long. It can forage for itself at about three
months, but continues to be suckled by its mother from the teats under her flippers,
for at least another yearbefore it becomes independent.
Conservation
In the past, dugongs were hunted for their meat, oil and even their teeth and
bones. Now, pollution and the loss of sea grass beds through dredging, and the
setting of nets which entangle dugongs and eventually drown them, are threatining the
population.
The population is currently estimated at around 30,000 and it is listed as vulnerable by
the World Conservation Union.